風船
ふうせん · fuusen · JLPT N2 · noun
balloon
🎈 風 = wind, 船 = boat: a wind-boat that floats up, like a balloon.
Fuusen is 'wind' + 'ship'. A balloon is a little craft carried by air, so the word literally means a wind-vessel.
船 — boat radical 舟 + 㕣 (phonetic)
船 is a semantic-phonetic compound. The left side 舟 depicts a boat and gives the meaning, while the right side 㕣 originally suggested the sound. Together they refer to a ship or vessel, a meaning that has stayed stable since early seal script.